US5153506A - Apparatus for measuring a winding temperature of electric machines - Google Patents

Apparatus for measuring a winding temperature of electric machines Download PDF

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Publication number
US5153506A
US5153506A US07/568,830 US56883090A US5153506A US 5153506 A US5153506 A US 5153506A US 56883090 A US56883090 A US 56883090A US 5153506 A US5153506 A US 5153506A
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United States
Prior art keywords
reference voltage
voltage source
machine
mains
measuring
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Expired - Fee Related
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US07/568,830
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Gerhard Trenkler
Reinhard Wedekind
Reinhard Maier
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Siemens AG
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Siemens AG
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Assigned to SIEMENS AKTIENGESELLSCHAFT, ORGANIZED UNDER THE LAW OF FEDERAL REPUBLIC OF GERMANY reassignment SIEMENS AKTIENGESELLSCHAFT, ORGANIZED UNDER THE LAW OF FEDERAL REPUBLIC OF GERMANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: TRENKLER, GERHARD, WEDEKIND REINHARD, MAIER, REINHARD
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/18—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer
    • G01K7/20—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a linear resistance, e.g. platinum resistance thermometer in a specially-adapted circuit, e.g. bridge circuit
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines

Definitions

  • the present invention relates generally to an apparatus for measuring the winding temperature of electric machines, and more particularly to apparatus for measuring the winding temperature by using an a.c. reference voltage source, a current detector and a measuring and evaluating device.
  • a method is also disclosed in E & I, Anno 105, Issue 7/8, pp 315 to 318, which makes possible a measurement of the rotor temperature of squirrel-cage induction machines without using thermal sensors.
  • the rotor temperature is calculated from the variation of the voltage across terminals after switching off a machine that operating without a load and from the time constants of the rotor.
  • the present invention is directed to the problem of further developing an apparatus for measuring the winding temperature across the line feed of an operating electric machine while dispensing with the additional sensors, and the capacitors which are connected in series to the machine, through which the entire power received by the machine would have to flow.
  • the present invention solves this problem by connecting an a.c. reference voltage generating one or more a.c. reference voltages in series with one or more phases of the mains which supply the electric machine such that one or more predetermined, non-line frequency, voltage components are added to the line voltage.
  • This generates a current with the predetermined frequencies that pass through the winding of the machine.
  • the current is detected by a current detector and then measured by a measuring and evaluating device.
  • the conductance of the winding can be calculated, which then leads to a determination of its temperature, since the winding conductance is temperature dependent.
  • the present invention is capable of detecting the actual winding conductance while the machine is operating.
  • the actual, average winding temperature can be derived from this variable.
  • This winding temperature is an important parameter for operating a machine, since the permissible maximum temperature should not be exceeded for long period of time for reasons of machine longevity, yet for reasons of economy, operation should take place at the margin of the nominal values.
  • the a.c. reference voltage source is designed as a voltage generator supplying a resonance transformer, then the voltage from the generator can be decoupled from the mains.
  • the a.c. reference voltage source is designed as a voltage generator supplying a broadband transformer, then the voltage from the generator can again be decoupled from the mains. However, the capacitor, which is required for the resonance voltage transformer, is no longer necessary, and the available bandwidth for the a.c. reference signal becomes relatively large.
  • the transformer can be dispensed with so that the lower frequency can be freely selected.
  • the a.c. reference voltage source is designed as a d.c. voltage source which is modulated by the predetermined frequency, then again, a transformer is not required and the lower frequency limit can be freely selected. This design is preferred when a pulse-controlled a.c. converter is not present.
  • the a.c. reference voltage source is designed as a mains voltage modulator
  • the a.c. reference signal can be derived directly from the supplying main.
  • apparatus consisting of controlled equivalent conductances or susceptances as well as switches can be used as are disclosed in "Modualtions Kunststoff in der horrentechnik” [Modulating Methods in Telecommunications], R. Mausl, UTB Huthig Verlag, Heidelberg, 1976, Chapter 1.3, pp. 35-55, the disclosure of which is hereby incorporated by reference. Since in this case the current and voltage are simultaneously influenced, it is necessary to measure both variables as well as to form their quotients in order to calculate the temperature.
  • a.c. reference signals consisting of at least three different frequency ranges, which are evaluated separately, are generated by the mains voltage modulator, then the use of signals with multiple frequencies, such as noise, is possible.
  • a.c. reference voltage source In addition to the indicated possible designs for the a.c. reference voltage source, the simultaneous evaluation of a.c. reference signals of different frequencies or frequency ranges has proved advantageous for a distinct possibility of identifying deterministic interferences. Since these interferences are narrow-banded and have known frequency differentials, they can be identified by simply comparing the amplitudes of several a.c. reference signals of different frequencies. For example, if two of at least three a.c. reference signals are the same and are therefore able to be evaluated within the limits of measuring uncertainty, the third can be discarded.
  • the current detector is also several possible designs for the specific embodiment of the current detector. If the current detector is designed as a resonance transformer, then in addition to the voltaic separation from the mains, the line-frequency signals are effectively damped. However, an additional capacitor is required. If the current detector is designed as a broadband transformer, then also, as in the case of the resonance transformer, there is a voltaic separation from the mains. The capacitor in this case is superfluous and the available bandwidth becomes large.
  • the current detector is designed as a shunt.
  • the current transformer can be dispensed with; however, the voltaic separation must also be dispensed with.
  • a simple design for the measuring and evaluating device is by means of selective amplitude measurements.
  • the measuring and evaluating device is designed as a spectral analytical device, preferably one using the Fast-Fourier transformation, parasitic frequencies can be identified and the frequency resolution can be high.
  • the measuring and evaluating device is designed as a synchronous demodulator which is controlled by the a.c. reference voltage source, then selectivity and noise reduction are attainable with regard to stochastic noise.
  • the a.c. reference voltage source is modulated by means of a generator with a band spreading function, and the broadband a.c. reference signal is supplied to a synchronous modulator functioning as the current detector, then a reduction of noise is attainable with regard to deterministic interferences.
  • a.c. reference voltage source and the current detector are designed as several devices present in each phase in the polyphase mains, to which devices for monitoring the symmetry of the signals are connected in order to identify a short circuit to a winding and/or an exposed conductive part.
  • the rotary speed of the machine can also be detected if a device is switched onto the a.c. reference voltage source.
  • the device derives a signal which is proportional to the rotary speed of the machine from an a.c. voltage which is fed into an induction machine, which can appear on the terminals of the machine as a voltage and/or current signal.
  • FIG. 1 is a block diagram of the general structure of a one phase design.
  • FIG. 2 is a principle design of the a.c. reference voltage source.
  • FIG. 3 is a block diagram of the general structure of a one phase design having an additional device for measuring rotary speed.
  • the upper frequency limit at which a nearly load-free measurement is possible depends on the type of machine. It lies advantageously in the range below 10 Hz.
  • a suitable a.c. reference voltage source 2 is connected in series to the mains 1 supplying the machine 5 such that this predetermined, non-line, low frequency voltage is added geometrically to the line voltage and a current of this frequency is driven through the winding of the machine 5 and the mains 1.
  • This current is detected by a current detector 3 and is supplied to a measuring and evaluating device 4.
  • the amplitude of the a.c. reference voltage is to be selected such that no significant additional heating of the machine 5 takes place, i.e., for example, the amplitude of the a.c. reference voltage does not exceed 1-2% of the line voltage. In the case of rotating electric machines, no interfering instants arise.
  • the current is in proportion to the conductance to be measured and can be directly evaluated. If the demand for a constant a.c. reference voltage is not satisfied, then this voltage shall also be measured.
  • the conductance or the resistance can then be determined.
  • These types of modules are known e.g. from Tietze, Schenk, "Halbleiterscibiltechnik” [Semiconductor Switch Engineering], Springer Verlag Berlin, 1986, 8th edition, Page 344, the disclosure of which is hereby incorporated by reference.
  • the aforementioned resistance is the series connection of the winding and the mains resistance. The latter can be ignored, however, if it is less than the winding resistance by some orders of magnitude. This requirement is satisfied in customary mains. If the mains resistance is to be included in the measurement in order to increase accuracy, then it is to be measured and taken into account in the evaluation by means of simple subtraction, since it is constant in practice.
  • the a.c. reference voltage source 2 has, e.g., a simple function generator feeding the primary of a resonance transformer, i.e., a transformer which is operated by means of a capacitor preferably in series resonance, and the secondary of the resonance transformer is coupled to the mains 1 supplying the machine 5.
  • a resonance transformer i.e., a transformer which is operated by means of a capacitor preferably in series resonance
  • the secondary of the resonance transformer is coupled to the mains 1 supplying the machine 5.
  • line-frequency reactions to the function generator are effectively avoided.
  • the demands on the function generator are few; its source resistance should not considerably impair the quality of the resonant circuit.
  • the decoupling of the generator voltage form the mains 1 is advantageous.
  • the resonance transformer is to be adjusted to the stable a.c. reference frequency which must lie safely above its lower frequency limit which is determined by the transformer.
  • the demands on the frequency stability are high, since otherwise amplitude errors and phase faults can appear.
  • the decoupling of the generator voltage from the mains 1 is advantageous.
  • a capacitor is unnecessary.
  • the available bandwidth for the a.c. reference signal is large.
  • the source resistance of the feeding generator must be very low and the transmission ratio of the transformer is not permitted to be too low, since otherwise the line-frequency voltages which are transferred to the generator side do not drop sufficiently at the source resistance of the generator and can endanger it.
  • the existing modulator can be used to generate the desired a.c. reference voltage by additionally modulating it with the desired a.c. reference frequency.
  • the lower frequency limit can be selected freely.
  • a switch 7 is controlled by a pulse generator 6 and switches the d.c. voltage source 8 temporarily in series to the mains 1.
  • the switch 7 is preferably a known configuration of semiconductor switches.
  • the pulse generator 6 actuates this switch 7 at the a.c. reference frequency.
  • a modulation of the d.c. voltage which is delivered by the d.c. voltage source 8 takes place with the a.c. reference frequency and simultaneously an addition of the product of modulation to the line voltage takes place.
  • the effective value of the a.c. reference voltage can be determined by way of the d.c. voltage and/or by way of the pulse width of the control signal of the pulse generator 6. In the output of the d.c.
  • the voltage source 8 there is usually a filter capacitor present which is temporarily connected in series to the machine 5 and to the mains 1 for the duration of the pulse. Current, and thus only a negligible part of the machine power, flows through it only for the duration of the control signal of the pulse generator 6. By appropriately selecting the control times, the effort for this capacitor can be minimized.
  • the lower frequency limit of the a.c. reference signal is also able to be freely selected in the case of this configuration.
  • the d.c. voltage source 8 lies at the mains potential. It is therefore necessary to design the supply lines for the pulse generator 6 and the d.c. voltage source 8 such that the requisite electrical isolation is guaranteed.
  • the current detector 3 which is used in FIG. 1 can be designed as a resonant current transformer.
  • a current transformer is operated in parallel resonance at the stable a.c. reference frequency by means of a capacitor. Therefore, the line-frequency signals in its output signal are effectively damped so that the further processing is simplified.
  • the a.c. reference frequency must lie safely above the lower frequency limit of the transformer; the demands on frequency stability are great, since otherwise amplitude errors and phase faults can appear.
  • the current detector 3 in a design for the current detector 3 as a broadband current transformer, a simple current transformer is used whose lower frequency limit lies below the a.c. reference frequency. In this case, a capacitor can be dispensed with. The available bandwidth becomes large. Of further advantage is the voltaic separation of the output signal from the mains potential. Line-frequency output signals must be sufficiently damped in the measuring and evaluating device 4 by means of conventional low pass filters.
  • the most economical possibility of a design for the current detector 3 is by using a simple shunt.
  • a current transformer can be dispensed with; there is no lower frequency limit.
  • the shunt is included in the measuring result. Therefore, it must be dimensioned such that its influence is negligible. In case this is not possible, it can be taken into account in the evaluation by means of a simple subtraction since its value is known. A voltaic separation from the mains potential is not present in this design.
  • the a.c. reference voltage and/or reference current is derived by means of selective filters which are adjusted to the a.c. reference frequency and are supplied to a known averaging unit.
  • the average is calculated in the customary manner, and, as described above, is converted into the winding temperature.
  • a sufficient signal to noise ratio between the useful and interference signals is necessary. It can be improved by the high quality of the selective filter and/or great time constants of the averaging unit. The rate of detection of temperature changes increases in this case.
  • the a.c. reference voltage and/or the reference current are evaluated with a conventional spectrum analyzer. Parasitic frequencies can be identified and the frequency resolution can be very high, if needed. Known analog analyzers or preferably digital Fast-Fourier transform analyzers can be used.
  • the voltage source can be modulated by a suitable band spreading operation.
  • modulating rapid changes in frequency or phases can be considered as modulating methods.
  • the modulated signal is used as an a.c. reference to the synchronous demodulation of the current signal.
  • This type of a configuration a reduction of noise is attainable with regard to deterministic interferences.
  • frequency components can be generated which are based on the modulation of the a.c. reference voltage. Since they are in proportion to rotary speed, they can be used to measure rotary speed.
  • the products of modulation can be converted into a noise-free frequency range so that a simple evaluation is possible.
  • an a.c. reference voltage source 2 is connected in series to the mains 1 supplying the machine 5.
  • the a.c. reference voltage source 2 can be switched to deliver an additional non-line frequency voltage which is advantageously different from the temperature a.c. reference frequency.
  • the current detector 3 delivers a current- and/or voltage signal in which frequency components are contained which are in proportion to the rotary speed.
  • the a.c. reference voltage source 2 and the current detector 3 are not to be designed as resonance transformers in the case of differing a.c. reference frequencies. Modules for the measuring means 9 are known.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Tests Of Circuit Breakers, Generators, And Electric Motors (AREA)
US07/568,830 1989-08-22 1990-08-17 Apparatus for measuring a winding temperature of electric machines Expired - Fee Related US5153506A (en)

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Application Number Priority Date Filing Date Title
DE3927698 1989-08-22
DE3927698 1989-08-22
DE4013174 1990-04-25
DE4013174 1990-04-25

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US (1) US5153506A (de)
EP (1) EP0414052B1 (de)
JP (1) JPH0389129A (de)
AT (1) ATE90451T1 (de)
CA (1) CA2023651A1 (de)
DE (1) DE59001684D1 (de)
DK (1) DK0414052T3 (de)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5483841A (en) * 1994-07-18 1996-01-16 Martin Marietta Energy Systems, Inc. Method and apparatus for monitoring motor operated valve motor output torque and power at valve seating
US5512843A (en) * 1993-11-15 1996-04-30 Martin Marietta Energy Systems, Inc. Monitoring method and apparatus using high-frequency carrier
US5661386A (en) * 1993-11-22 1997-08-26 Lockheed Martin Energy Systems, Inc. Method for assessing in-service motor efficiency and in-service motor/load efficiency
US5977742A (en) * 1998-03-12 1999-11-02 Kabushiki Kaisha Toshiba Electric vehicle control device
US20030040670A1 (en) * 2001-06-15 2003-02-27 Assaf Govari Method for measuring temperature and of adjusting for temperature sensitivity with a medical device having a position sensor
US20070268023A1 (en) * 2006-05-19 2007-11-22 Dooley Kevin A System and method for monitoring temperature inside electric machines
US20110040483A1 (en) * 2009-08-17 2011-02-17 Aws Convergence Technologies, Inc. Method and Apparatus for Detecting Lightning Activity
US20120056613A1 (en) * 2010-09-08 2012-03-08 Phoenix Contact Gmbh & Co. Kg Method and device for the detection of current asymmetries in three-phase circuits
US20120330483A1 (en) * 2011-06-27 2012-12-27 Gm Global Technology Operations Llc. Rotor temperature estimation for an electric vehicle
US20130127412A1 (en) * 2011-11-22 2013-05-23 GM Global Technology Operations LLC System and method for controlling exchange of current
US20130214811A1 (en) * 2010-10-07 2013-08-22 Cajetan Pinto Detection Of A Missing Stator Slot Wedge In An Electrical Machine
FR3036184A1 (fr) * 2015-05-11 2016-11-18 Univ D'artois Procede d'evaluation d'une temperature
US9891345B2 (en) 2012-01-18 2018-02-13 Earth Networks, Inc. Using lightning data to generate proxy reflectivity data
US11316413B2 (en) * 2016-02-01 2022-04-26 Vitesco Technologies GmbH Connection between a winding and a circuit board

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DE19743046C1 (de) * 1997-09-29 1999-04-29 Siemens Ag Verfahren und Vorrichtung zum Erfassen der Betriebstemperatur von Motoren
DE19754351C1 (de) * 1997-12-08 1999-08-12 Maxon Motor Gmbh Verfahren und Vorrichtung zur Messung der Temperatur einer Wicklung
DE10126300C1 (de) 2001-05-30 2003-01-23 Infineon Technologies Ag Verfahren und Vorrichtung zum Messen einer Temperatur in einem integrierten Halbleiterbauelement
DE10143222C1 (de) 2001-09-04 2003-04-17 Siemens Linear Motor Systems G Temperaturmeßvorrichtung für einen Elektromotor
DE10149982B4 (de) * 2001-10-10 2005-11-03 Siemens Ag Verfahren zur Ermittlung der Temperatur einer elektrischen Spule sowie zugehörige Vorrichtung
DE10235433B4 (de) * 2002-04-25 2012-03-01 Zf Friedrichshafen Ag Verfahren zur Bestimmung einer Temperatur eines Fluids, insbesondere einer Getriebeöltemperatur
DE102004046275B4 (de) * 2003-09-23 2006-12-21 Saxotec Gmbh & Co.Kg Vorrichtung zur Überwachung der Temperatur von Hochspannung führenden Baugruppen
DE102019134777A1 (de) * 2019-12-17 2021-06-17 Metabowerke Gmbh Elektrowerkzeug, Messeinrichtung und Verfahren zum Betrieb eines Elektrowerkzeugs

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5512843A (en) * 1993-11-15 1996-04-30 Martin Marietta Energy Systems, Inc. Monitoring method and apparatus using high-frequency carrier
US5661386A (en) * 1993-11-22 1997-08-26 Lockheed Martin Energy Systems, Inc. Method for assessing in-service motor efficiency and in-service motor/load efficiency
US5483841A (en) * 1994-07-18 1996-01-16 Martin Marietta Energy Systems, Inc. Method and apparatus for monitoring motor operated valve motor output torque and power at valve seating
US5977742A (en) * 1998-03-12 1999-11-02 Kabushiki Kaisha Toshiba Electric vehicle control device
US20030040670A1 (en) * 2001-06-15 2003-02-27 Assaf Govari Method for measuring temperature and of adjusting for temperature sensitivity with a medical device having a position sensor
US20070268023A1 (en) * 2006-05-19 2007-11-22 Dooley Kevin A System and method for monitoring temperature inside electric machines
US9614472B2 (en) 2006-05-19 2017-04-04 Pratt & Whitney Canada Corp. System for monitoring temperature inside electric machines
US8604803B2 (en) * 2006-05-19 2013-12-10 Pratt & Whitney Canada Corp. System and method for monitoring temperature inside electric machines
US20110040483A1 (en) * 2009-08-17 2011-02-17 Aws Convergence Technologies, Inc. Method and Apparatus for Detecting Lightning Activity
US8531179B2 (en) * 2010-09-08 2013-09-10 Phoenix Contact Gmbh & Co. Kg Method and device for the detection of current asymmetries in three-phase circuits
US20120056613A1 (en) * 2010-09-08 2012-03-08 Phoenix Contact Gmbh & Co. Kg Method and device for the detection of current asymmetries in three-phase circuits
US20130214811A1 (en) * 2010-10-07 2013-08-22 Cajetan Pinto Detection Of A Missing Stator Slot Wedge In An Electrical Machine
US8847620B2 (en) * 2010-10-07 2014-09-30 Abb Research Ltd. Detection of a missing stator slot wedge in an electrical machine
US9166518B2 (en) * 2011-06-27 2015-10-20 GM Global Technology Operations LLC Rotor temperature estimation for an electric vehicle
US20120330483A1 (en) * 2011-06-27 2012-12-27 Gm Global Technology Operations Llc. Rotor temperature estimation for an electric vehicle
US20130127412A1 (en) * 2011-11-22 2013-05-23 GM Global Technology Operations LLC System and method for controlling exchange of current
US8912754B2 (en) * 2011-11-22 2014-12-16 GM Global Technology Operations LLC System and method for controlling exchange of current
US9891345B2 (en) 2012-01-18 2018-02-13 Earth Networks, Inc. Using lightning data to generate proxy reflectivity data
FR3036184A1 (fr) * 2015-05-11 2016-11-18 Univ D'artois Procede d'evaluation d'une temperature
US11316413B2 (en) * 2016-02-01 2022-04-26 Vitesco Technologies GmbH Connection between a winding and a circuit board

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EP0414052A1 (de) 1991-02-27
CA2023651A1 (en) 1991-02-23
JPH0389129A (ja) 1991-04-15
DK0414052T3 (da) 1993-10-04
EP0414052B1 (de) 1993-06-09
DE59001684D1 (de) 1993-07-15
ATE90451T1 (de) 1993-06-15

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